Abstract

A Gram-stain negative, yellow-pigmented, motile, pleomorphic bacterium, designated strain CBA4602T, was isolated from the gut of the sea cucumber Stichopus japonicus, which was collected from Jeju Island in the Republic of Korea. In a phylogenetic analysis based on the 16S rRNA gene, strain CBA4602T belonged to the order Sphingomonadales in the class Alphaproteobacteria. The 16S rRNA gene sequence similarity between strain CBA4602T and ‘Citromicrobium bathyomarinum’ JF-1, the most closely related strain having nonvalidly published name, was 98.4%, followed by 95.2–96.7% identities with sequence of the other closest strains in the genus Erythrobacter. Strain CBA4602T had bacteriochlorophyll a and carotenoids. Strain CBA4602T grew in 0–10% (w/v) NaCl, at 10–42°C and pH 6.0–8.0, with optimal growth in 1–2% NaCl, at 30–37°C and pH 7.0. Strain CBA4602T was positive for catalase and oxidase activities and was able to hydrolyse gelatine and Tween 20 and 40, but not starch, Tween 80 or L-tyrosine. The G+C content of genomic DNA from strain CBA4602T was 68.0 mol% and Q-10 was the major detected isoprenoid quinone. The polar lipids were three unidentified phospholipids, three unidentified glycolipids, and two unidentified lipids. The dominant fatty acids were anteiso-C15:0, C16:0, anteiso-C17:0 and C18:0. As considering the current taxonomic status of the genus ‘Citromicrobium’ and polyphasic taxonomic analyses, strain CBA4602T represents a novel genus and species. The name Citrimicrobium luteum is proposed for the type strain CBA4602T (=KACC 17668T =JCM 19530T).

• Keywords: Citrimicrobium luteum;sea cucumber;Stichopus japonicus;gut bacterium;polyphasic taxonomy